Chrome Version: 57.0.2958.0
Chrome OS Version: 9034.0.0

Steps To Reproduce:
(1) Turn on ChromeVox.
(2) Insert an SD card with some new photos in /DCIM folder
(3) Focus on the Cloud Backup button by [tab] key.

Actual Result:
ChromeVox tells current status of the Cloud Backup, but doesn't tell what the button actually does.
Other buttons describes the actions the user can take by each button, like "Delete", "Search", and "Thumbnail view".

Proposals:

* Plan A: Change tooltip messages.

- When new photos found:
current: "Ready to backup 1 new photos"
proposal: "Import 1 new photos to Google Drive"

- When all files are already backed up:
current: "All Backed Up!"
proposal: "Cloud backup: all selected files are backed up" when selecting 1 or more files, and
          "Cloud backup: all files under the media folder are backed up" otherwise.


* Plan B: Make the button always work as "Show Cloud backup details".

Currently the left half part of the Clound Backup icon works as a shortcut of "BACK UP" button in the details panel. Eliminate this shortcut flow and make the button always annotated as "Show Cloud backup details".
We need to make the details panel accessible before doing that.
https://bugs.chromium.org/p/chromium/issues/detail?id=475184


How frequently does this problem reproduce? (Always, sometimes, hard to
reproduce?)
Always

What is the impact to the user, and is there a workaround? If so, what is
it?
This is a potential accessibility issue.